Relationship between lens density measurements by Pentacam Scheimpflug imaging and torsional phacoemulsification parameters

Abstract

RESULTS: In the present study, 125 eyes from 125 patients were evaluated. Mean age was 69.7±9.4y (range: 48-88y), and 61 men and 64 women were included. The highest and lowest values of U/S total time, torsional U/S time, CDE, and Estimated fluid use were 0.70 - 158.90s, 0.70-158.50s, 0.11-42.65, and 21-98 mL in groups, respectively. Significant differences were found among PND groups. When the relationship between phacoemulsification dynamics and PND values were evaluated, there were significant correlations between PND value and total ultrasound time (r=0.767; P<0.01), torsional ultrasound time (r=0.767; P<0.01), CDE (r=0.758; P<0.01), and amount of fluid used (r=0.602; P<0.01).

Full text

·Original article·
Relationship between lens density measurements by
Pentacam Scheimpflug imaging and torsional
phacoemulsification parameters
Suleyman Demircan1, Mustafa Atas1, Murat Koksal2, Emine Pangal1, Isa Yuvaci1, Altan
G觟ktas1
1Eye Clinic, Kayseri Training and Research Hospital, Kayseri
38010, Turkey
2Kayseri Modern Dunya Hospital, Kayseri 38010, Turkey
Correspondence to: Suleyman Demircan. Eye Clinic,
Kayseri Training and Research Hospital, Kayseri 38010,
Turkey. dr. s. demircan@ hotmail. com
Received: 2013-11 -30摇 摇 Accepted: 2014-08 -01
Pentacam Scheimpflug 成像测量晶状体密度与
torsional 超声乳化参数间的关系
Suleyman Demircan1,Mustafa Atas1,Murat Koksal2,Emine
Pangal1,Isa Yuvaci1,Altan G觟ktas1
(作者单位:138010 土耳 其开赛里,开赛里培 训 研 究 医 院 眼 科;
238010 土耳其开赛里,开赛里 Modern Dunya 医院)
通讯作者:Suleyman Demircan. dr. s. demircan@ hotmail. com
摘要
目的:评价运用 Pentacam Scheimpflug 成像测量晶状体核
密度与 torsinal 超声乳化动力学参数(如:运用于老年核性白
内障患者的超声能量水平、液体留存时间及液体量)间的关系。
方法:此研究为前瞻性双盲研究。瞳孔扩大后运用
Pentacam Scheimpflug 成像进行测量。白内障的等级由
pentacam 核 密 度 测 定 法 [pentacam nucleus densitometry,
PND;又名 Pentacam 核分段(Pentacam nucleus staging,PNS)
软件]自 主 分 为 1到5个 等 级。超声乳化术后,自动在
Infiniti Ozil IP 超声乳 化系统监 视 器上计算并显 示 总超声
(U/ S)时间、累计耗散能、Torsional U / S 时间以及估算液体
的使用情况。组间差异运用单因素方差分析(ANOVA)进
行评定,多组分析运用 Tamhane 测试法,PND 测量的晶状体
密度与 torsinal 超声乳化动力学参数间的关系运用 Spearman
相关分析进行评定。界定 P<0. 05 时具有统计学意义。
结果:此项研究包括 125 例患者 (125 眼) ,平均 年 龄为
69. 7 依9. 4 岁(范围:48 ~ 88 岁) ,其 中 61 例男性、64 例女
性。U / S 总时间、torsional U / S 时间、CDE 及估算液体使用
情况的范围分别为 0 . 70 ~ 158. 9 s,0. 70 ~ 158. 5s,0. 11 ~
42. 65 和21 ~ 98 mL. PND 组间数据有统计学差 异。评估
超声乳化动力学参 数 与 PND 数据间关系后得出 PND 数
据与总超声时间( r = 0. 767 ; P<0. 01)、torsional 超声时间
( r = 0. 767 ; P<0 . 01)、CDE( r = 0. 758; P <0. 01)及液体使
用量( r = 0 . 602; P<0. 01)均有显著相关性。
结论:白内障手 术前运用 PND 评分法获得核密度的客观
程度可为超声乳化术中的参数提供可靠的预见性。因此,
对每一位患者进行每一单项超声乳化参数的评估,有助于
降低超声乳化能量的使用量,减少内皮细胞丢失和类固醇
的使用,加速视力的恢复。
关键词:torsional 超声乳化;pentacam;沙氏成像;晶状体密
度测定
引用:Demircan S, Atas M, Koksal M, Pangal E, Yuvaci I, G觟ktas
A. Pentacam Scheimpflug 成像 测 量晶状体密 度 与 torsional 超声
乳化参数间的关系.国际眼科杂志 2014;14(10) :1739-1743
Abstract
誗AIM:To evaluate the relationship between the density
values of the lens nucleus measured using Pentacam
Scheimpflug imaging and torsional phacoemulsification
dynamics such as the level of ultrasound energy,as well
as the duration and amount of fluid used in patients with
age-related nuclear cataract.
誗METHODS:This was a prospective observer -masked
study. Pentacam Scheimpflug imaging was performed
following pupil dilation. The cataracts were automatically
graded from 1to 5using pentacam nucleus densitometry
(PND), also known as Pentacam nucleus staging (PNS)
software by the same observer. After phacoemulsification,
total Ultrasound (U / S )time,Cumulative dissipated
energy (CDE) , Torsional U / S time,and Estimated fluid
use were automatically calculated and displayed on the
monitor of Infiniti OZiL IP phacoemulsification system.
One -way analysis of variance (ANOVA)was used to
assess differences between groups. The Tamhane test
was used for multiple group analysis. Spearman
correlation analysis was used to assess the relationship
between lens density measured by PND and the dynamics
of torsional phacoemulsification. P< 0 .05 was considered
statistically significant.
誗RESULTS:In the present study,125 eyes from 125
patients were evaluated. Mean age was 69.7 依 9.4y
(range:48 - 88y) , and 61 men and 64 women were
included. The highest and lowest values of U / S total
time,torsional U / S time,CDE,and Estimated fluid use
were 0.70 - 158.90s,0.70 - 158.50 s,0.11 -42.65,and 21- 98
mL in groups,respectively. Significant differences were
found among PND groups. When the relationship
between phacoemulsification dynamics and PND values
were evaluated,there were significant correlations
between PND value and total ultrasound time (r= 0.767;P<
9371
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0.01) , torsional ultrasound time (r= 0.767;P< 0 .01) , CDE
(r= 0.758;P< 0.01 ) , and amount of fluid used (r= 0.602;
P<0 .01).
誗CONCLUSION:An objective degree of nucleus density
obtained by PND scoring before cataract surgery may
allow antecedent determination of intraoperative
phacoemulsification parameters. Thus,individualized
phacoemulsification parameters should be developed for
each patient. This will lead to the use of a smaller amount
of phacoemulsification energy,resulting in decreased in
endothelial cell loss,quicker and better visual healing,
and less steroid use.
誗KEYWORDS:torsional phacoemulsification;pentacam;
scheimpflug imaging;lens densitometry
DOI:10. 3980 / j. issn. 1672-5123 . 2014. 10. 01
Citation:Demircan S, Atas M, Koksal M, Pangal E, Yuvaci I,
G觟ktas A. Relationship between lens density measurements by
Pentacam Scheimpflug imaging and torsional phacoemulsification
parameters. Guoji Yanke Zazhi(Int Eye Sci) 2014;14(10):1739-1743
INTRODUCTION
The quantitative detection of degree of cataract density is
an indispensable component of epidemiological and
clinical studies on cataract[1] . Grading the density of cataract
is of importance when it comes to identification of the potential
risk factors of cataract development, documentation of
cataract, pharmaceutical research on cataract treatment, and
preoperative prediction of phacoemulsification surgery dynamics.
Clinically, the approaches used to grade density of cataract
are classified into subjective and objective methods[2,3] .
Subjective methods include the Lens Opacities Classification
System version III (LOCS III ) , Wisconsin Cataract Grading
System, Oxford Clinical Cataract Classification and Grading
System, and Laser Slit Lamp Assessment[2- 5] . LOCS III has
gained wide acceptance among these classifications. In this
grading system, the degree of cataract is determined through
comparison to a standardized set of photographs under
biomicroscopy[4] . In several studies, it has been shown that
LOCS III is highly reproducible[4,5] . However, it is also
associated with reliability issues due to differences in the
assessment caused by intra - observer and inter - observer
variations, as in all subjective grading systems[6,7] . The ideal
grading system for cataract would be both reproducible and
objective.
Concerns regarding LOCS III promote attempts to develop
objective methods such as Scheimpflug - based photography
and slit imaging. The Topcon SL - 45 , Zeiss Scheimpflug
video camera, and Nidek EAS - 1000 have been used in
clinical practice[8 -12] . Currently, Scheimpflug - based
Pentacam camera system ( Oculus, Wetzlar, Germany) has
gained popularity. The Pentacam Scheimpflug imaging system
is an easy, rapid, and objective grading system with a rapid
learning curve and no ocular contact[7] . This system provides
three - dimensional images of anterior ocular segment by
capturing images in less than 2 seconds. The images captured
are converted to numeric values by the specialized software in
the system; therefore, several parameters for the anterior
chamber, cornea, and lens can be assessed[7-9 ] .
Measurement of density of the lens nucleus using this system
is highly reproducible[6,10,11,13] . This high reproducibility is
not only true for intra-observer variation, but also for inter-
observer variation[11,13] . The objective degree of nucleus
density obtained by Pentacam nucleus densitometry scoring
before cataract surgery may allow antecedent determination of
intraoperative phacoemulsification parameters.
The aim of the present study was to evaluate the relationship
between the density values of the lens nucleus measured using
Pentacam Scheimpflug imaging and torsional
phacoemulsification dynamics such as the level of ultrasound
energy, as well as the duration and amount of fluid used in
patients with age-related nuclear cataract.
SUBJECTS AND METHODS
This prospective observer - masked study was conducted at
Kayseri Training and Research Hospital between March and
June 2012. It was carried out in accordance with the Helsinki
Declaration and approved by the hospital蒺s Institutional Review
Board. All patients gave written informed consent before
participation.
The study included 125 eyes from 125 patients. Exclusion
criteria were previous ocular trauma or intraocular surgery,
pseudoexfoliation syndrome, preoperative pupillary width less
than 6 mm, an anterior chamber depth less than 2 . 4 mm
centrally, and systemic disease affecting vision or disease
involving the eyes (diabetic retinopathy, age-related macular
degeneration, or uveitis) and white cataracts. All patients
underwent a comprehensive ophthalmologic examination
including visual acuity assessment, intraocular pressure
measurement, biomicroscopy, and dilated fundus
examination. Before Pentacam Scheimpflug imaging, pupils
were dilated using 2% tropicamide, 2 . 5% phenylephrine,
and 1% cyclopentolate. Pentacam Scheimpflug imaging was
performed by an experienced technician. The density of the
lens nucleus was automatically graded between 0 and 5 by the
device using Pentacam Nucleus Staging (PNS) software.
All surgeries were performed under topical anesthesia by the
same experienced surgeon ( S. D. ). Phacoemulsification was
performed with the quick chop technique using an Infiniti誖
OZiL Intellegent Phaco ( IP) system( Alcon Laboratories, Fort
Worth, TX, USA) and the 0. 9 mm mini-flared 45毅 Kelman
Aspiration Bypass system ( ABS ) phaco tip. Torsional
phacoemulsification settings for the quick chop technique were
as follows: ultrasound power, 85% at continuous linear
mode; vacuum limit, 350 mm Hg linear; aspiration flow rate,
32 mL / min linear; dynamic rise, +2 ( IP) mode; and bottle
height, 95 cm. All clear corneal incisions were made with 2郾 2
mm keratome. Viscoat (Alcon Laboratories, Fort Worth, TX,
USA) ( Sodium hyaluronate 3. 0 % - Chondroitin sulphate
4郾 0% ) was used to reform and stabilize AC and protect
corneal endothelium. A 5. 0 -5. 5 mm continue curvilinear
capsulorhexis was made using a ultrata capsulorhexis forceps
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Table 1Comparison of intraoperative parameters in Pentacam nucleus staging (PNS)groups
Variables Pentacam nucleus staging ( PNS) groups
1( n= 29 ) 2( n= 32) 3( n= 31) 4( n= 17) 5( n= 16)
Total Ultrasound time 23. 62依12. 28a38 . 94 依14. 78a48. 51 依17. 56a79. 88依15. 87 a84. 16依31 . 68 a
Torsional Ultrasound time 23. 61依12. 28a38 . 86 依14. 80a48. 40 依17. 39a79. 67依15. 74 a83. 96依31 . 66 a
Cumulative dissipated energy ( CDE) 4. 62依2. 87a8. 25依3. 88a10 . 91依4. 91 a19. 58依5 . 72a21. 24依9. 80a
Estimated fluid use 38. 66依8. 68a48 . 69依10. 54 a48. 58依10 . 97 a59. 29依11. 70 a65 . 69依14. 58 a
Values are expressed as mean依SD. astatistically significant differences.
( Katena products, Inc, New Jersey,USA ) . Cortex aspiration
was performed using a coaxial irrigation / aspiration tip. A
hydrophobic acrylic intraocular lens ( AcrySof SA60AT, Alcon
Laboratories, Fort Worth, TX, USA) ) was inserted into the
capsular bag with same injector system ( Monarch III - D
Catridge, Alcon Laboratories) . Sodium hyaluronate 1. 0 %
(Provisc, Alcon Laboratories, Fort Worth, TX, USA ) was
used for intraocular implantation of the lens. Sodium
hyaluronate 1% ( Provisc, Alcon Laboratories, Fort Worth,
TX, USA ) was removed from AC and capsular bag using
coaxial I / A system. Following surgery, total ultrasound time,
torsional ultrasound time, cumulative dissipated energy
(CDE) , and amount of fluid used-which were automatically
calculated for each patient by the Alcon- Infiniti device- were
obtained from the device.
Statistical Analysis 摇 Were performed by using SPSS for
Windows version 16. 0 ( SPSS Inc, Chicago, IL, USA ) .
Normality was tested using the Shapiro-Wilk test. One- way
analysis of variance ( ANOVA) was used to assess differences
between groups. The Tamhane test was used for multiple
group analysis. Data were expressed as mean 依 standard
deviation. Spearman correlation analysis was used to assess
the relationship between lens density measured by Pentacam
nucleus densitometry ( PND ) and the dynamics of torsional
phacoemulsification. P< 0. 05 was considered statistically
significant.
RESULTS
In the present study, 125 eyes from 125 patients were
evaluated. Mean age was 69. 7依9 . 4 y ( range: 48 - 88y) , and
61 men and 64 women were included. Table 1 presents the
PND measurement groups and total ultrasound time, torsional
ultrasound time, CDE, and amount of fluid used. Significant
differences were found among groups. When the relationship
between phacoemulsification dynamics and PND values were
evaluated, there were significant correlations between PND
value and total ultrasound time (r= 0. 767; P<0. 01; Figure 1),
torsional ultrasound time ( r= 0. 767; P< 0. 01; Figure 2) ,
CDE (r= 0. 758; P< 0. 01; Figure 3) , and amount of fluid
used (r= 0 . 602; P<0. 01; Figure 4) .
We stratified patients according to PND scores (graded from 1
to 5) into three groups as follows: patients with PND scores of
1 (mild cases) ; those with PND scores of 2 or 3 ( moderate
cases); and those with PND score of 4 or 5 ( severe cases) .
It was found that patients with a PND score of 1 significantly
differed from patients in the other PND groups, while there
Figure 1 摇 Relationship between total U/ S time and Pentacam
lens nucleus densitometry (PND)groups.
Figure 2 摇 Relationship between Torsional U / S time and
Pentacam lens nucleus densitometry (PND)groups.
Figure 3 摇 Relationship between CDE and Pentacam lens
nucleus densitometry (PND)groups.
was no significant difference between patients with PND scores
of 2 or 3 and those with PND scores of 4 or 5.
1471
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Figure 4 摇 Relationship between estimated fluid use and
Pentacam lens nucleus densitometry (PND)groups.
DISCUSSION
In the present study, we evaluated the relationship between
density of the lens nucleus estimated using the PND system
and different phacoemulsification parameters. A significant,
strong correlation was detected between PND score and total
ultrasound time, torsional ultrasound time, CDE, and amount
of fluid used. In a study using both LOCS III and a Pentacam
Scheimpflug camera system to determine the degree of density
of lens nucleus, Kim et al[10 ] evaluated several parameters
using same torsional phacoemulsification system. The authors
found a strong correlation between density of the lens nucleus
and total ultrasound time, torsional ultrasound time, and
CDE. Although their findings are consistent with our results,
they reported that the amount of fluid did not correlate with
PND scoring[10] . A similar finding was detected in another
study using the LOCS III grading system[ 11] . In contrast,
another study, as well as our own, detected a positive
correlation between amount of fluid used and PND scoring[14 ] .
Kim et al[10 ] published other important findings that PND
scoring has a stronger positive correlation with CDE when
compared to LOCS III and PND measurements are superior to
LOCS III in the detection of lens nucleus status. In recent
study, Gupta et al[15] reported that both systems had a linear
correlation with total U / S power, CDE and fluid use;
however, PND grading system had a stronger correlation with
these phacoemulsification parameters.
There are three major criteria in the identification of cataract
severity and the need for surgery[16] . These include degree of
lens opacity, acuity of vision, and alteration in quality of life.
The incidence of nuclear cataract increases with advancing
age. In nuclear cataract, the mechanisms underlying the
worsening in vision are scattering of light and opacity in the
lens nucleus following refractive changes in lens material[6 ,17] .
There are many systems that detect and grade nuclear
opacities. It is impossible to eliminate observer-related errors
in LOCS III and other subjective methods widely used for this
purpose. However, the Pentacam Scheimpflug camera system
is an objective system that provides information about the
density of the lens nucleus[7,8,18] . This system enables the
anterior and posterior cortical regions of the lens to be
differentiated[ 13,19] .
In cataract surgery, most of the phacoemulsification energy
used is expended on the removal of the lens nucleus[12,14,18] .
Thus, detection of the true density of the lens and
preoperative identification of phacoemulsification parameters
can provide surgical advantages. However, most cataract
surgeries are initiated as a result of routinely used parameters
and minor modifications are carried out during surgery. This
results in the use of excessive phacoemulsification energy in
patients with lower lens nucleus density, and causes
prolongation of phacoemulsification time, total ultrasound
time, and increased CDE due to insufficient power in those
with high lens nucleus density. As mentioned previously, we
can classify patients into three groups according to PNS
software before cataract surgery and provide individualized
nomogram phacoemulsification parameters for PNS value in
each patient. A similar correlation was detected in another
study using same phacoemulsification system as ours. In
addition, Chikamoto et al[20 ] found similar findings to ours,
using a different phacoemulsification system and different
cataract analysis device based on Scheimpflug imaging.
In a study in which patients who underwent standard cataract
surgery were compared to those who underwent cataract
surgery with individualized phacoemulsification parameters
according to nucleus density measured by PND scoring,
Nixon[14 ] reported that there was a significant decrease in
effective phacoemulsification time, amount of fluid used, and
total phacoemulsification time. A significant difference was
found between patients with a PND score of 1 and those with
PND scores of 4 or 5 in the group underwent surgery with
individualized phacoemulsification parameters. Effective
phacoemulsification time, amount of fluid used, and total
phacoemulsification time were increased by higher density of
lens nucleus. These findings are in accordance with our
results. In our study, CDE was evaluated in addition to the
above-mentioned parameters, showing a positive correlation.
Pentacam nucleus staging software has some limitations arising
from not only distortion at refractive surface but also disability
of sampling technology due to insufficient mydriasis, presence
of lens tilted and white cataracts[18,21] .
In conclusion,the objectivity of PND scoring means that it is
likely to be an appropriate monitoring system in
epidemiological studies investigating the development of
nuclear cataract and the assessment of drugs preventing or
inducing cataract. In addition, an objective degree of nucleus
density obtained by PND scoring before cataract surgery may
allow antecedent determination of intraoperative phacoemulsification
parameters. Thus, individualized phacoemulsification parameters
should be developed for each patient. This will lead to the use of
a smaller amount of phacoemulsification energy, resulting in
decreased in endothelial cell loss, quicker and better visual
healing, and less steroid use[12,22,23] .
2471
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